1. Technical Field of the Invention
The present invention relates to inducing and/or stimulating hair growth and/or retarding hair loss by topically/systemically administering to an individual in need of such treatment an effective amount of at least one compound which is an agonist with respect to RXR-type retinoid receptors.
This invention also relates to novel cosmetic/therapeutic compositions comprising such retinoid receptor agonists for promoting hair growth and/or retarding hair loss.
2. Description of the Prior Art
In human subjects the growth of the hair and its renewal are principally determined by the activity of the hair follicles. This activity is cyclic and essentially entails three phases, namely, the anagenic phase, the catagenic phase and the telogenic phase.
The active anagenic phase, or growth phase, which lasts for several years and during which the hair elongates, is succeeded by a very short and transitory catagenic phase which lasts for a few weeks, followed by a rest or quiescent phase, designated the telogenic phase, which lasts for a few months.
At the end of the rest period, the hair falls out and an new cycle begins. The head of hair thus undergoes permanent renewal and, of the approximately 150,000 hairs on a human head, at any given instant, approximately 10% are at rest and will therefore be replaced within a few months.
However, various causes may lead to a considerable temporary or permanent loss of hair. Alopecia, for example, is essentially due to a disturbance of hair renewal, which leads, in a first stage, to acceleration of the frequency of the cycles at the expense of the hair quality and then at the expense of its quantity. A gradual thinning of the head of hair occurs, and the so-called "end" or "terminal" hairs at the down stage recede. Certain regions are preferentially affected, in particular the temples and the front of the head in men, and, in women, diffuse alopecia of the crown is observed.
The term "alopecia" comprehends an entire family of afflictions/conditions of the hair follicle, the final consequence of which is the permanent partial or general loss of hair. In a large number of cases, early hair loss occurs in genetically predisposed individuals and it affects men in particular. This type of hair loss is more particularly androgenetic or androgenic or, alternatively, androgeno-genetic alopecia.
Active agents for eliminating or reducing alopecia, and, in particular, for inducing or stimulating hair growth or for retarding hair loss, have long been desiderata in the cosmetics and pharmaceutical industries.
From this perspective, a great number of very diverse active compounds such as, for example, 2,4-diamino-6-piperidinopyrimidine 3-oxide or "Minoxidil," described in U.S. Pat. Nos. 4,139,619 and 4,596,812, or, alternatively, its many derivatives, such as those described, for example, in EP-0,353,123, EP-0,356,271, EP-0,408,442, EP-0,522,964, EP-0,420,707, EP-0,459,890 and EP-0,519,819, have to date been proposed.
Need continues to exist in this art, however, for other active species for modulating hair growth/loss that are more active and/or less toxic.